Hi, If someone could explain to me what is linux and where to get it and how to runs it.
thanks...

answer to question #1
answer to question #2, you can get it here
And its not an IT, there are many different flavors of linux which are called distrobutions.
and how to run it is by downloading an ISO file, burn it to a cd, put it in your cd rom, reboot your computer, go through the setup which will run if your computer is set to boot from your cdrom, and then before you know it you'll be on the desktop.

With your very "simple" questions, you will get very simple answers. It obviously sounds like this is going to be your first time, and your just going to have to install it and start playing with it, and of course read read read, learn learn learn.. Easy as that.

also check out distrowatch.org

Your questions are very broad. There are many sites that will help you.

IMHO, what I would recommend is downlading knoppix and running it. It is what's called a LIVE! distrobution, meaning you don't have to install it. It runs from the CD drive and never touches the HD, so you won't lose any of your windows data. It'll give you a chance to play. That's what I did.

Thanks for helping i'm a C# programmer but i never tryied linux so thanks for help

You should try it. It's lots of fun. You can even program in linux and do other things.